How to thread a copper pipe

Preparing for die-cutting

Before cutting a thread with a die on a rod or pipe, you must select a tool of the required diameter and pitch. The die itself is a nut with conical cutting teeth with holes for fastening in the wrench. Dies can be solid, split, sliding, have a round, square or hexagonal shape.

First of all, you need to select the material and tool of the required diameter. Below is a table of correspondence of the most popular diameters for metric, inch and pipe threads with an example of the selection of a workpiece for an M6 thread

As you can see from the table, for threading M6 we need a rod with a diameter of 5.8 mm. For larger thread diameters, there is an allowable minimum and maximum value for the thickness of the rod. It cannot be violated. if the diameter is exceeded, you risk breaking the die, if the value is less than the minimum, you will get a weak thread.

Before you start cutting an external thread with a die, in addition to the tool itself and the workpiece, you need a wrench of a suitable shape and size, as well as machine oil. After that, you can proceed directly to the cutting itself.

Pipe cutting

Do you like to do home improvement work with your own hands, without involving various craftsmen for this? Self-installation or repair not only allows you to save money on calling specialists, but also greatly increases your self-esteem, because it is true?

In the process of installing communications, it is often necessary to prepare threads on pipes. We have to find ways not to spoil the product.

We will tell you how to cut a thread using different tools, which method is preferable to use in a given situation. The article discusses the methods available for implementation to an unqualified performer. The features of cutting different types of threads and the equipment used in this are highlighted.

The presented material is provided with visual photographic materials depicting the tools for performing the work. A video with recommendations will help you to understand in detail all the intricacies of this process.

Pipe thread classification

The term “pipe” has a privileged position in the field of plumbing. This term is classified with an eye to a group of standards that determine the criteria for the connections of various elements of plumbing structures.

For example, pipe thread size is indicated by a numerical value that indicates the pipe bore standard, but not the physical thread diameter.

In practice, pipe threads are used:

  • cylindrical (G / BSPP),
  • conical (R / BSPT),
  • round for shut-off sanitary fittings (Kr),
  • inch cylindrical (American standard NPSM),
  • inch conical (American standard NPT).
thread, copper, pipe

It is recommended for a locksmith, whose main working area is household facilities, to take as a basis the conditional division of pipe threads into two main types:

  • cylindrical (G),
  • conical (R).

It is with these two types that a home locksmith who serves household plumbing equipment, who lays water supply or heating pipes, most often has to deal with.

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Pipe cutting is performed in the following cases:

Thread cutting steps

To cut external threads, you need:

  • If there is an old thread on the pipe, first you need to cut this section. To do this, fix the pipe in a vice and use a trimming machine. Make sure that the cut is smooth and strictly perpendicular to the axis of the pipe;
  • Next, you need to use a grinder and remove the outer chamfer at the cut. This is necessary for a smoother start of the thread;
  • Assemble the tool and install the required die in diameter;
  • Slowly start twisting the die in a circle, while do not forget that after passing every 2-3 turns, you need to scroll in the opposite direction, for a clearer threading.
  • After cutting the threads to the desired length, remove all metal filings with a brush and check the quality of the threads by tightening the nut.

For internal threading:

  • First you need to determine what thread diameter you need. To do this, use a vernier caliper and measure the thread on the object you are going to screw in;
  • If required, drill a hole using an electric drill and the required drill diameter;
  • Remove metal filings and start cutting. To do this, fix the pipe in a vice, take a tap of the required diameter and begin to gently twist it in the right direction.
  • As for the external thread, after 2-3 turns, it is required to drive the tap in the opposite direction. Do not forget to lubricate the tap and the cutting area during this action.
  • Clean the pipe from metal filings and check for correct threading.
thread, copper, pipe

In more detail, the stages of cutting can be seen in a special video.

Thread cutting order

Before starting cutting, the outside of the pipe or workpiece must be chamfered at an angle of 45 °. This is necessary to facilitate the first turns and fix the die.

thread, copper, pipe

It is necessary to take into account that the die can have several numbers, most often 2. In this case, after cutting the rough thread, it is necessary to alternate through each of the numbers for the final formation of the thread profile.

The BEST 25 Copper Pipe Tips & Tricks EVER! | GOT2LEARN

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How to thread a pipe at home?

For self-threading on a metal pipe, you will have to master the technique for performing this procedure, as well as familiarize yourself with some of the features. It is not easy to do this at home, but it is possible. To do this, you need to prepare the desired tool and do it yourself, as in the video, to cut.

A few words about GOST on pipe thread

In conditions of work with gaseous and liquid media, according to GOST 6111, if it is necessary to introduce detachable connections into pipeline diagrams, it is allowed to manufacture such connections on a threaded base.

Possible is the execution of not only pipe, but also tapered thread (GOST 3662).

Despite the rare use of tapered threads in pipe connections, it is considered to be more convenient in terms of screw-on / make-up characteristics.

It should be recalled that the taper angle of a tapered thread is directly related to parameters such as pitch and diameter. The admissible value of this angle cannot be less than 26 °. The standard value of the angle of the top of the profile on a tapered thread is 60 °.

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Pipe threads are distinguished by their characteristic feature. they have a rounded top of the profile. Subject to cutting standards, the rounding is 10% of the thread radius.

With this cutting technology, it is possible to achieve a significant reduction in internal stresses on a small metal area occupied by a threaded profile.

The established tolerances of GOST 6357, along with cylindrical and tapered threads, provide for execution on pipes with metric threads.

Here the standard of the angle of inclination is 55 °, which is due to the increase in the number of turns in the section along the length equal to the section with a different type of thread.

The result is a connection with a higher degree of tightness, but the labor intensity when using such connections increases.

The existing GOST installations also provide for the possibility of performing thrust and trapezoidal threads on pipes. But in practice, these types of cuts are not used due to their low operational strength.

In plumbing work, different ways of connecting pipes are used. The choice of the method largely depends on the material of the pipeline and its “area of ​​responsibility”. Threaded joining of parts is recommended to be used in areas accessible for periodic revision.

How to Thread Pipe; A Beginner’s Tutorial

Information on alternative methods of connecting pipes is presented in the articles:

How to thread a copper pipe

If you need to manually cut external threads for a pipe connection, make a stud or a bolt for a nut with a metric thread, a simple but rather effective tool is most often used. a die. The thread preparation process is quite simple if you follow the instructions below exactly.

On stainless pipe

When it comes to threading stainless pipe, the task is complicated by the fact that the metal used is quite hard. Therefore, the appropriate steel grade of the die should be selected for cutting. In this case, the marking P18, or better R18F2, would be a suitable option. The letter “F” means that the material contains a regulating additive of vanadium up to 2%. In addition, P9 dies can be used for threading stainless pipes.

thread, copper, pipe

If you pick up a die of an inappropriate brand, then as a result you can be left without a die and without a thread. In some cases, threading is only possible on the shaft with a cutter.

Instrument composition

An electromechanical threading kit called “klupp” is used in conjunction with a set of radial dies of various diameters designed for threading on pipe workpieces of any dimension. In addition to the device itself, you will need the following tools and materials for threading:

  • Taps for fast tapping of internal threads.
  • Mechanical vise used for fixing tube blanks.
  • Grinder for the preparation of threading areas.
  • Lubricating oils.

Immediately, we draw your attention to the fact that working with an electric sander is allowed only with gloves and protective glasses.

Thread cutting steps

To cut external threads, you need:

A set of necessary tools

  • If there is an old thread on the pipe, first you need to cut this section. To do this, fix the pipe in a vice and use a trimming machine. Make sure that the cut is smooth and strictly perpendicular to the axis of the pipe;
  • Next, you need to use a grinder and remove the outer chamfer at the cut. This is necessary for a smoother start of the thread;
  • Assemble the tool and install the required die in diameter;
  • Slowly start twisting the die in a circle, while do not forget that after passing every 2-3 turns, you need to scroll in the opposite direction, for a clearer threading.
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Advice. Always use oil or special lubricant to make slicing easier. If this is not at hand, you can use a simple “old-fashioned” method and grease the plate with lard.

  • After cutting the threads to the desired length, remove all metal filings with a brush and check the quality of the threads by tightening the nut.

For internal threading:

  • First you need to determine what thread diameter you need. To do this, use a vernier caliper and measure the thread on the object you are going to screw in;
  • If required, drill a hole using an electric drill and the required drill diameter;
  • Remove metal filings and start cutting. To do this, fix the pipe in a vice, take a tap of the required diameter and begin to gently twist it in the right direction.
  • As for the external thread, after 2-3 turns, it is required to drive the tap in the opposite direction. Do not forget to lubricate the tap and the cutting area during this action.
  • Clean the pipe from metal filings and check for correct threading.

In more detail, the stages of cutting can be seen in a special video.

Pipe cutting

Internal threading

Internal threading

Before threading a pipe in its inner cavity, you will need to measure the diameter of the pipe hole. Based on the data received, you can select a working tool (tap) of the required size. Make sure that the length of the pipe section protruding from the wall is several millimeters longer than the threaded part to be cut.

After you have finally decided on the required diameter of the inner hole, you should re-drill it to a size suitable for threading.

In the process of reaming, you need to carefully monitor the position of the inserted part of the drill, which should not deviate from the vertical.

Upon completion of the preparatory operations, a tap of the required diameter is inserted into the pipe hole with a simultaneous clockwise rotation of its base. Rotation is carried out using the so-called “knob” included in the tool kit.

The procedure for preparing an in-line thread involves the use of the following working tool:

    tap under the designation, designed for preliminary (rough) “run” of the thread. The design of this tap is such that when using it, up to 70% of the material is removed;

Thus, to obtain a high-quality and full-fledged thread, you first have to “walk” along the inner cavity of the pipe with a tap, and then repeat the same operation using a tap. All these works should be accompanied by the introduction of small portions of machine oil into the working area.

How to thread a pipe near a wall. How to thread a pipe near a wall. and photo instructions

How to thread a copper pipe

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